Mysterious & # 39; bag & # 39; of underwater gas discovered in the East China Sea can be a huge energy source or a & # 39; ticking time bomb & # 39 ;, researchers say
- Japanese researchers detected the trapped gas with seismic waves
- Gases that are likely to have built up thanks to magma rising in this area of crust spreading
- The reservoir may be made from the methane fuel or the greenhouse gas CO2
- Other gas bags can exist in similar geological environments around the world
A mysterious gas block under the seabed off the coast of Japan has been discovered by geologists who explored the earth with seismic waves.
The composition of the gas is unknown, but it is probably made from methane or carbon dioxide, produced thanks to magma rising from the depths of the earth.
The newly discovered reserve can be an untapped natural resource if it is dominated by methane gas that can be used as fuel, the researchers said.
Alternatively, such trapped gases could form a ticking time bomb of greenhouse gases, ready to escape into the atmosphere and cause climate shifts.
Anyway, the researchers note that this reservoir is probably not alone – and that others are expected to be hidden both in the neighborhood and in similar environments around the world.
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A mysterious gas block beneath the sea floor off the coast of Japan has been discovered by geologists exploring the earth with seismic waves
Seismologist Andri Hendriyana and colleagues from Kyushu University of Japan discovered the large reservoir using seismic pressure waves.
These – similar to those generated by earthquakes – can reveal the nature of the rocks beneath the seabed as they bounce off.
& # 39; Seismic pressure waves generally travel slower through gases than solids & # 39 ;, co-author Andri Hendriyana explains.
& # 39; By estimating the speed of seismic pressure waves through the ground, we can therefore identify underground gas reservoirs and even get information about how saturated they are. & # 39;
The new study used a special computational technique with which the researchers were able to map cross sections of the material under the seabed in much more detail than was previously possible.
& # 39; In this case we found low speed bags along the rotating axis near Iheya North Knoll in the middle of the Okinawa trough, indicating areas filled with gas, & # 39; added Dr. Hendriyana.
Such rotating axes are where the tectonic plates of the earth are slowly pulled apart by so-called continental drift, allowing hot magma to seep out of the mantle beneath.
This magma can release both carbon dioxide and methane, and stimulates both microbial growth and interactions with organically-rich sediments that also produce these gases.
The team believes that some of these gases get trapped under the seabed – either under layers of impenetrable clay or a lid made from a methane-containing ice – building up to the kind of reservoir they saw off the Japanese coast.
WHAT ARE TECTONIC PLATES?
Tectonic plates are composed of the earth's crust and the upper part of the mantle.
Below is the asthenosphere: the warm, viscous rock conveyor on which tectonic plates run.
The earth has fifteen tectonic plates (photo) that together have shaped the shape of the landscape that we see around us today
Earthquakes usually occur at the borders of tectonic plates, where one plate protrudes below another, pushes another up, or where the plate edges scrape past each other.
Earthquakes rarely occur in the center of plates, but they can happen when old faults or fissures reactivate far below the surface.
These areas are relatively weak compared to the surrounding plate and can easily slip and cause an earthquake.
& # 39; Although many people focus on people's greenhouse gases, there is also a wide variety of natural resources & # 39 ;, paper author Takeshi Tsuji added.
& # 39; Large-scale gas reservoirs along a rotating axis can be another source of greenhouse gases that we need to monitor. & # 39;
& # 39; Or they may prove to be an important natural resource. & # 39;
To be the latter, the reservoir must primarily be filled with methane, which, unlike carbon dioxide, can be used as a fuel. The researchers currently do not know which of the two gases forms the largest part of the captured reservoir.
Either way, both are greenhouse gases that can have significant environmental effects if they are released into the atmosphere quickly.
This body of gas may not be alone, the researchers report.
& # 39; Zones as we have explored are not uncommon along gaps, & # 39; said Professor Tsuji.
& # 39; I expect similar reservoirs to exist elsewhere in the Okinawa trough, as well as other sediment-covered continental back-arc basins around the world. & # 39;
The full findings of the study were published in the journal Geophysical Research Letters.
"We found low speed bags along the rotating axis near Iheya North Knoll in the middle of the Okinawa trough, indicating areas filled with gas," said Dr. Hendriyana
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